The Country Fire Authority (CFA) says a large bushfire burning in the Alpine region could flare up again today.

The blaze has burnt through more than 20,000 hectares of rugged terrain and fire activity has increased in the Sambas Mine area.

Although conditions have eased overnight, a watch and act alert is still in place for Harrietville.

CFA incident controller Stephen Grant says the back-burning work that has been carried out should help fire fighting efforts today.

"We had some very dry air come in over the fire and the fire got very active to the south of Harrietville," he said.

"We've been conducting burning operations basically from the town to the south. [It's] going particularly well at the moment. The fire's quietened right down."

Meanwhile, the CFA says crews have strengthened the containment lines around two other bushfires in central Victoria.

The fires at Kerrie, near Mount Macedon, started over the weekend, and a watch and act warning is in place for the area.

The bigger of the two fires has burnt 50 hectares of land, and a smaller spotfire has burnt 10 hectares.

The CFA's Craig Brittain says some excellent work was done overnight.

"At this stage, we'll be getting some ground observers to come down, just to give us a bit more intelligence from the fire ground and also we'll upgrade our sum mapping to make sure that we have done our job," he said.

And fire crews continue to try to contain the huge Aberfeldy fire that is threatening the Licola and Glenfalloch areas, in the state's north-east.

The fire has burned through more than 82,521 hectares.

A spot fire in rocky, steep terrain at Burgoyne Gap has burnt through 764 hectares.